Footwear sole with a stiffness adjustment mechanism

Abstract

The invention is an article of footwear having a sole comprised of one or more support elements formed of a resilient, compressible material. The support elements are designed such that the positions of one or more bands that encircle the exterior surface of the support elements may be altered such that the deflection characteristics of the support elements are changed. In order to facilitate the repositioning of the bands, the support element includes an access indentation defined by the exterior surface or flanges that are secured to each band.

Description

BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to footwear. The invention concerns, more particularly, a sole for footwear that includes a mechanism for adjusting stiffness characteristics of the sole.[0004]2. Description of Background Art[0005]Sole design for modern athletic footwear is generally characterized by a multi-layer construction that includes an outsole, midsole, and insole. The midsole typically includes a soft, foam material to attenuate impact forces and absorb energy when the footwear contacts the ground during athletic activities. Other prior art midsoles utilize fluid or gas-filled bladders of the type disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 to Marion F. Rudy. Although foam materials succeed in providing cushioning for the foot, foam materials also impart instability that increases in proportion to midsole thickness. For this reason, footwear design often involves a balance of cushioning and stability.[0006...

AI Technical Summary

Benefits of technology

[0014]The present invention is an article of footwear that includes an upper for receiving a foot of a wearer and a sole attached to the upper. The sole incorporates at least one support element that includes an exterior surface, at least one band that encircles the exterior surface, and a structure that facilitates movable positioning of the band with respect to the exterior surface to thereby alter deflection and stiffness characteristics of the support element.

[0015]In a first embodiment of the invention a flange extends outward from the band. The purpose of the flange is to permit the wearer to gain a secure grip upon the band when repositioning the band. In a second embodiment of the invention, each support element includes an access indentation inscribed in the exterior surface. The purpose of the access indentation is to facilitate repositioning of the band along the length of the support element by permitting the wearer to effectively gain control of the band. Because the band encircles the exterior surface and restricts outward movement of the support element, positioning of the band in an area of high support element deflection restricts such deflection, thereby increasing the stiffness of the support element. In order to ensure that the band remains in the chosen position, band indentations may extend around the support element. Accordingly, the wearer may position the band in one of a plurality of possible positions, potentially defined by the band indentations, to adjust deflection and stiffness characteristics of the sole.

Problems solved by technology

Other prior art midsoles utilize fluid or gas-filled bladders of the type disclosed in U.S. Pat. Nos. 4,183,156 and 4,219,945 to Marion F. Rudy. Although foam materials succeed in providing cushioning for the foot, foam materials also impart instability that increases in proportion to midsole thickness.

Pronation, the inward roll of the foot while in contact with the ground, although normal, can be a potential source of foot and leg injury, particularly if it is excessive.

The use of soft cushioning materials in the midsole of running shoes, while providing protection against impact forces, can encourage instability of the sub-talar joint of the ankle, thereby contributing to the tendency for over-pronation.

This instability has been cited as a contributor to “runners knee” and other athletic injuries.

While making such movements, footwear instability may lead to excessive inversion or eversion of the ankle joint, a primary cause of ankle sprain.

The downward incline on the interior of the footwear caused by the differential compression, in conjunction with the momentum of the athlete's body, creates a situation wherein the shoe rolls towards the lateral side, causing an ankle sprain.

The preceding example particularly arises when footwear incorporates a midsole with cushioning qualities that do not provide sufficient stability.

Such devices take the form of rigid members, elastic materials, or straps that add to the overall weight of the footwear, make the article of footwear cumbersome, or restrict plantar flexion and dorsi flexion.

Columns designed with straight walls that do not contain grooves have a greater tendency to buckle.

Although bands 36 provide an effective method of adjusting the stiffness of support element 32, the prior art designs are difficult for a wearer to adjust.

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